In order to support long-term security requirements, it is advantageous if a user, in particular a device or field device, can flexibly support different cryptographic methods. For example, different crypto algorithms are intended to be able to be carried out or different key lengths or keys are intended to be able to be generated for different purposes or applications. Such a device therefore requires a multiplicity of private keys for different asymmetrical cryptographic methods. Such asymmetrical encryption methods are used, for example, for authentication with communication partners in the authentication and key agreement protocol, for example the Secure Socket Layer or Transport Layer Security SSL/TLS, or for issuing an attestation data structure. An asymmetrical method can also be used to create a digital signature or to encrypt and decrypt data.
In the case of a standard-compliant Version 2.0 Trusted Platform Module TPM, it is known that such a module contains a secret parameter, a so-called platform primary seed. This is a seed value or a starting value from which a secret algorithm-specific key suitable for this purpose can be derived by means of an algorithm-specific key derivation function. As a result, such a platform module can support different cryptographic methods without having to store a separate cryptographic key for each of these methods. However, the use of a primary platform starting value is restricted to deriving a private key for a particular asymmetrical method.